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Jefferson National Expansion MemorialArch and Old Courthouse at Night
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Jefferson National Expansion Memorial
Photo Album May 11, 1805
Dinosaur cartoon  

Did You Know?
On September 10, 1804 on Cedar Island, in South Dakota, William Clark discovered the fossilized remains of the ribs, backbone and teeth of a plesiosaur. Plesiosaurs were animals who lived at the same time as the dinosaurs, but swam rather than walking on land. Clark thought it was a giant fish bone!
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Last Updated: February 17, 2009 at 10:59 EST